As David Radler gets slapped with a sentence for fraud in a downtown Chicago courtroom today, his old boss, dethroned press baron Conrad Black, is working on an appeal to have his own sentence and the guilty verdict against him thrown out.

Radler, 65, is expected to get two years and five months behind bars under a deal he worked out with prosecutors for pleading guilty to one count of fraud and agreeing to take the stand and testify against Black, 63.

Prosecutors were seeking to jail Black for as long as 24 years after a jury convicted him in July of looting millions from shareholders in his newspaper company, Hollinger International, and removing boxes of documents to cover up his crimes.

But last week the media mogul got only a 61/2-year term and was ordered to report to prison on March 3. Legal experts say the low sentence is probably largely because of the relatively light sentence for Radler – who the judge last week described as “at least as culpable” in the fraud.

Immediately after Judge Amy St. Eve read the sentence, Black huddled with his team of high-profile appeals lawyers, including Andrew Frey, a New York-based lawyer who helped get the obstruction conviction overturned against former tech-banking star Frank Quattrone.

The obstruction conviction is seen to be the weakest one against Black, but experts said the three fraud charges, which accused him of stealing $6.1 million, will be harder to overturn.

“As a general proposition, appellate courts give the lower courts the real benefit of doubt and are very reluctant to overturn jury verdicts,” said Lee Dunst, a former federal prosecutor who’s now a lawyer with Gibson Dunn & Crutcher. “But it can be done.”